INDIANAPOLIS — After the most trying week of his presidential bid, Senator Barack Obama sought to reframe and reinvigorate his candidacy on Saturday by asking Democrats to disregard “phony ideas, calculated to win elections instead of actually solving problems” and to seize an opportunity to change Washington.

In a speech here, on the final weekend of campaigning before the Indiana and North Carolina primaries on Tuesday, Mr. Obama urged voters to move beyond the political controversies that have dominated the Democratic nominating fight and stirred skepticism about his strength as a general election candidate.

“That’s the only way I can win this race,” Mr. Obama said, “if you decide that you’ve had enough of the way things are, if you decide that this election is bigger than flag pins or sniper fire or the comments of a former pastor — bigger than the differences between what we look like or where we come from or what party we belong to.”

As Senator Hillary Rodham Clinton appealed to voters in North Carolina, holding a breezy chat session with a few hundred mothers and later appearing before Nascar enthusiasts, she highlighted her support for suspending the federal gas tax this summer. Mr. Obama derided the idea as “a Shell game — literally,” drawing distinctions with Mrs. Clinton and Senator John McCain of Arizona, the presumptive Republican nominee.

Mr. Obama’s speech here underscored his efforts to retool his campaign — and fend off what his aides acknowledged was unexpected strength from Mrs. Clinton in Indiana and North Carolina — by forcefully returning to themes that had served him well in Iowa and other states, presenting himself as an outsider and an agent of change. He did not, at least on this day, seem prepared to end the campaign with harsh attacks on Mrs. Clinton.

In television commercials and in his public appearances, Mr. Obama confronted the issue Mrs. Clinton has put at the front of her campaign — a three-month moratorium on gas taxes — and tried to turn it against her, portraying her as being politically calculating and cynical. That left the two rivals pointedly arguing over one of the few major policy areas on which they disagree.

“Senator Clinton and Senator McCain have been using this issue to make the argument that I’m somehow out of touch,” Mr. Obama said. “Well let me tell you, only in Washington can you get away with calling someone out of touch when you’re the only one who thinks that 30 cents a day is enough to help people who are struggling in this economy.”

To applause, he added, “I think the American people are smarter than Washington gives us credit for.”

Photo

Senator Hillary Rodham Clinton with Gov. Michael F. Easley of North Carolina in Gastonia.Credit
Damon Winter/The New York Times

The gas-tax holiday has emerged as one of the most contentious issues of the race, with Mr. Obama calling the proposal a gimmick that would deplete a fund to build and repair bridges and roads and would cost thousands of jobs. Not so, Mrs. Clinton has said, suggesting to voters that Mr. Obama opposes extending them a break. Analysts estimate the plan would save drivers 30 cents a day.

For the first time since the Iowa caucus campaign, Mr. Obama was joined here by his daughters, Malia and Sasha, and his wife, Michelle. The imagery of the young family was intended to amplify his speech and remind voters of his biography.

The Obamas stopped at a park in Noblesville, dropped by the former home of a distant relative in Kempton and ended the evening at an ice cream social at a Lafayette roller rink. Each of the appearances, carefully choreographed, was intended to send a message of familiarity to voters.

Until recently, Mr. Obama was considered the candidate with the greater personal appeal and the more consistent message. But on Saturday, Mrs. Clinton offered sympathetic words to several hundred mothers about the problems of child care and teenage dating, while continuing to focus on the economy.

“I’ve always thought that toddlers and teenagers need about the same amount of attention,” Mrs. Clinton, of New York, said at a morning panel discussion on motherhood in Cary, N.C. The production notes on the day’s schedule showed that the stage had been set up to look like the set of “The View.”

Later, at the North Carolina Auto Racing Hall of Fame, Mrs. Clinton stood amid life-size cutouts of Nascar stars and one real, live one: Junior Johnson, who introduced the senator. “You know, our country is in trouble,” Mrs. Clinton said. “Junior, it’s in the ditch!”

But none of Mrs. Clinton’s comments won as loud a reaction as her indignant remark about the price of gas. “People get sick to their stomach when they fill up the gas tank,” she said to applause in Cary.

Both candidates focused on the states in which they appeared to be running behind, with Mrs. Clinton striving to cut Mr. Obama’s lead in North Carolina and Mr. Obama working to win over voters in Indiana, where Mrs. Clinton seems to have an edge.

But by evening, Mrs. Clinton was on her way back to Indiana for an appearance with the rocker John Mellencamp, a native of the state. And Mr. Obama, of Illinois, was planning a return appearance in North Carolina on Monday, a signal that the pair of primaries remained fluid and filled with uncertainty.

A version of this article appears in print on , on page A33 of the New York edition with the headline: As Tuesday Votes Loom, Obama Seeks Lift and Clinton Pushes Gas-Tax Plan. Order Reprints|Today's Paper|Subscribe